[floss] Update device migration LTKs and identity address

BlueZ uses the identity address as the device path. Update
Floss->BlueZ conversion to use identity address if available.
Also update local/peripheral LTKs if available.

Bug: 308981467
Test: Rust unit tests
Test: Manually inspect device cache files for BlueZ and Floss
Test: mma -j32
Flag: EXEMPT, floss change for ChromeOS only.
Change-Id: I903002e2e5f74a74d48bc8d269efe2968eaea296